Proceedings of the National Academy of Sciences of the United States of America (PNAS) is one of the world's most-cited multidisciplinary scientific serials. Since its establishment in 1914, it continues to publish cutting-edge research reports, commentaries, reviews, perspectives, colloquium papers, and actions of the Academy. Coverage in PNAS spans the biological, physical, and social sciences. PNAS is published weekly in print, and daily online in PNAS Early Edition. The PNAS impact factor is 9.737 and the Eigenfactor is 1.557 for 2012. PNAS is available by subscription.PNAS Online launched in January 1997 and now receives over 21 million hits per month. The site contains PDFs of all articles in PNAS dating back to 1915, and the full text, figures, tables, equations, and references dating back to November 1996.
PNAS articles are also published online before print in PNAS Early Edition as soon as they are accepted and final author changes are made.